Econstudentlog

Wikipedia articles of interest

i. Ironclad warship.

“An ironclad was a steam-propelled warship in the early part of the second half of the 19th century, protected by iron or steel armor plates.[1] The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. The first ironclad battleship, La Gloire, was launched by the French Navy in November 1859.[2] [...]

The rapid evolution of warship design in the late 19th century transformed the ironclad from a wooden-hulled vessel that carried sails to supplement its steam engines into the steel-built, turreted battleships and cruisers familiar in the 20th century. This change was pushed forward by the development of heavier naval guns (the ironclads of the 1880s carried some of the heaviest guns ever mounted at sea), more sophisticated steam engines, and advances in metallurgy which made steel shipbuilding possible.

The rapid pace of change in the ironclad period meant that many ships were obsolete as soon as they were complete, and that naval tactics were in a state of flux. Many ironclads were built to make use of the ram or the torpedo, which a number of naval designers considered the crucial weapons of naval combat. There is no clear end to the ironclad period, but towards the end of the 1890s the term ironclad dropped out of use. New ships were increasingly constructed to a standard pattern and designated battleships or armored cruisers. [...]

From the 1860s to the 1880s many naval designers believed that the development of the ironclad meant that the ram was again the most important weapon in naval warfare. With steam power freeing ships from the wind, and armor making them invulnerable to shellfire, the ram seemed to offer the opportunity to strike a decisive blow.

The scant damage inflicted by the guns of Monitor and Virginia at Battle of Hampton Roads and the spectacular but lucky success of the Austrian flagship Ferdinand Max sinking the Italian Re d’Italia at Lissa gave strength to the ramming craze.[30] From the early 1870s to early 1880s most British naval officers thought that guns were about to be replaced as the main naval armament by the ram. Those who noted the tiny number of ships that had actually been sunk by ramming struggled to be heard.[31]

The revival of ramming had a significant effect on naval tactics. Since the 17th century the predominant tactic of naval warfare had been the line of battle, where a fleet formed a long line to give it the best fire from its broadside guns. This tactic was totally unsuited to ramming, and the ram threw fleet tactics into disarray. The question of how an ironclad fleet should deploy in battle to make best use of the ram was never tested in battle, and if it had been, combat might have shown that rams could only be used against ships which were already stopped dead in the water.[32]“

This is how one of them looked like, click to view full size*:

ii. Allometry. John Hawks talked about this a bit in one of his lectures, I decided to look it up:

“Allometry is the study of the relationship of body size to shape,[1] anatomy, physiology and finally behaviour [...] Allometry often studies shape differences in terms of ratios of the objects’ dimensions. Two objects of different size but common shape will have their dimensions in the same ratio. Take, for example, a biological object that grows as it matures. Its size changes with age but the shapes are similar. [...]

In addition to studies that focus on growth, allometry also examines shape variation among individuals of a given age (and sex), which is referred to as static allometry. Comparisons of species are used to examine interspecific or evolutionary allometry [...]

Isometric scaling occurs when changes in size (during growth or over evolutionary time) do not lead to changes in proportion. [...] Isometric scaling is governed by the square-cube law. An organism which doubles in length isometrically will find that the surface area available to it will increase fourfold, while its volume and mass will increase by a factor of eight. This can present problems for organisms. In the case of above, the animal now has eight times the biologically active tissue to support, but the surface area of its respiratory organs has only increased fourfold, creating a mismatch between scaling and physical demands. Similarly, the organism in the above example now has eight times the mass to support on its legs, but the strength of its bones and muscles is dependent upon their cross-sectional area, which has only increased fourfold. Therefore, this hypothetical organism would experience twice the bone and muscle loads of its smaller version. This mismatch can be avoided either by being “overbuilt” when small or by changing proportions during growth [...] Allometric scaling is any change that deviates from isometry. [...]

In plotting an animal’s basal metabolic rate (BMR) against the animal’s own body mass, a logarithmic straight line is obtained. Overall metabolic rate in animals is generally accepted to show negative allometry, scaling to mass to a power ≈ 0.75, known as Kleiber’s law, 1932. This means that larger-bodied species (e.g., elephants) have lower mass-specific metabolic rates and lower heart rates, as compared with smaller-bodied species (e.g., mice), this straight line is known as the “mouse to elephant curve”.

iii. Arthropod.

“An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda (from Greek ἄρθρον árthron, “joint”, and ποδός podós “leg”, which together mean “jointed leg”), and include the insects, arachnids, crustaceans, and others. Arthropods are characterized by their jointed limbs and cuticles, which are mainly made of α-chitin; the cuticles of crustaceans are also biomineralized with calcium carbonate. The rigid cuticle inhibits growth, so arthropods replace it periodically by molting. The arthropod body plan consists of repeated segments, each with a pair of appendages. It is so versatile that they have been compared to Swiss Army knives, and it has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living animal species, and are one of only two animal groups that are very successful in dry environments – the other being the amniotes. They range in size from microscopic plankton up to forms a few meters long.”

Another way to put it – it’s these guys:

I thought the stuff on molting (Ecdysis) was interesting:

“The exoskeleton cannot stretch and thus restricts growth. Arthropods therefore replace their exoskeletons by molting, or shedding the old exoskeleton after growing a new one that is not yet hardened. Molting cycles run nearly continuously until an arthropod reaches full size.[22] [...] In the initial phase of molting, the animal stops feeding and its epidermis releases molting fluid, a mixture of enzymes that digests the endocuticle and thus detaches the old cuticle. This phase begins when the epidermis has secreted a new epicuticle to protect it from the enzymes, and the epidermis secretes the new exocuticle while the old cuticle is detaching. When this stage is complete, the animal makes its body swell by taking in a large quantity of water or air, and this makes the old cuticle split along predefined weaknesses where the old exocuticle was thinnest. It commonly takes several minutes for the animal to struggle out of the old cuticle. At this point the new one is wrinkled and so soft that the animal cannot support itself and finds it very difficult to move, and the new endocuticle has not yet formed. The animal continues to pump itself up to stretch the new cuticle as much as possible, then hardens the new exocuticle and eliminates the excess air or water. By the end of this phase the new endocuticle has formed. Many arthropods then eat the discarded cuticle to reclaim its materials.[22]

Because arthropods are unprotected and nearly immobilized until the new cuticle has hardened, they are in danger both of being trapped in the old cuticle and of being attacked by predators. Molting may be responsible for 80 to 90% of all arthropod deaths.[22]“

It’s a long article, and it has a lot of good stuff (and lots of links).

iv. Scottish independence referendum, 2014. I did not know about this.

v. Coordination game.

“In game theory, coordination games are a class of games with multiple pure strategy Nash equilibria in which players choose the same or corresponding strategies. Coordination games are a formalization of the idea of a coordination problem, which is widespread in the social sciences, including economics, meaning situations in which all parties can realize mutual gains, but only by making mutually consistent decisions. [...]

A typical case for a coordination game is choosing the side of the road upon which to drive, a social standard which can save lives if it is widely adhered to. [...] In a simplified example, assume that two drivers meet on a narrow dirt road. Both have to swerve in order to avoid a head-on collision. If both execute the same swerving maneuver they will manage to pass each other, but if they choose differing maneuvers they will collide. [...] In this case there are two pure Nash equilibria: either both swerve to the left, or both swerve to the right. In this example, it doesn’t matter which side both players pick, as long as they both pick the same. Both solutions are Pareto efficient. This is not true for all coordination games”

vi. Ostrogothic Kingdom. Of course Heather is the reason why I read that article. At its greatest extent, the kingdom looked roughly like this:

I have not yet read all of the relevant material covering this subject in Heather, so I don’t know the extent to which he (or others) disagrees with Bury (who seems to be the main source of the article). But if you didn’t know there was such a thing as an Ostrogothic Kingdom in the first place, reading the article will probably not be a step in the wrong direction.

vii. Speleology. Yet another one of those areas of research you have probably never thought about:

“Speleology (also spelled spelæology or spelaeology) is the scientific study of caves and other karst features, their make-up, structure, physical properties, history, life forms, and the processes by which they form (speleogenesis) and change over time (speleomorphology). The term speleology is also sometimes applied to the recreational activity of exploring caves, but this is more properly known as caving, spelunking or potholing. Speleology and caving are often connected, as the physical skills required for in situ study are the same.

Speleology is a cross-disciplinary field that combines the knowledge of chemistry, biology, geology, physics, meteorology and cartography to develop portraits of caves as complex, evolving systems.”

I thought the article on troglobites (small cave-dwelling animals which live permanently underground and cannot survive outside the cave environment), which it links to, was interesting too.

* I decided to present the readers with an alternative way to post images on the blog, which I’m considering applying in the future. I have been made aware that the current modus operandi, posting pictures full-size in the posts, is not always optimal given the readers’ preferences regarding browsers and which tools with which to access the site (‘modern gadgets’ vs PC). I should make it clear that if you read this blog using a PC in a firefox browser with a pretty standard screen resolution, it looks fine. Because that’s how I access and view the site.

I am, and have been for a very long time, afraid that the blog will turn too much into a wall of text and I keep reminding myself that I should take active countermeasures to prevent this from happening. I don’t care that much about illustrations and images, but I know that many people do. Is this way of presenting images which I have applied in the post – relatively small thumbs which you can click if you want to see them in full size – (much) better than the alternative?

One more thing. I know that it’s quite possible that the reason stuff like images sometimes look like crap is because the chosen theme for the blog is not optimal. But I also know that the last time I changed the theme, everything went to hell and it took me days to handle the problems which the theme change caused. That was, mind you, at a point in time where the number of posts was less than a fourth of what it is today. If I change the theme, it affects at least every post I’ve written in the last 4 years. I have no idea how it will impact stuff like videos. So even if the theme is not optimal, changing it is not an option if I can avoid it.

April 22, 2012 Posted by | biology, blogging, Game theory, Geology, history, Paleontology, wikipedia | 1 Comment

   

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